Fill valve assemblies are used in water storage tanks and the like for refilling the storage tank after a predetermined volume of water has been drained or used from the storage tank. In toilets, for example, fill valve assemblies are mounted in a toilet tank of the toilet for the purpose of refilling a toilet tank and a toilet bowl of the toilet after a flush actuation. Upon a flush actuation, a flapper valve in the toilet tank is opened. Water from the toilet tank flows into a toilet bowl of the toilet for purposes of flushing the toilet. The fill valve assembly typically includes a post supporting a water inlet valve. The post is affixed to a bottom wall of the toilet tank and extends through an opening or passageway in the bottom wall of the toilet tank. An inlet end of the post is coupled to and in fluid communication with a water supply line. The post routes supply line water to the inlet valve assembly. When the toilet is flushed, for example, by pushing on an arm of a flush handle mounted on the toilet tank, the flush handle actuation opens the flapper valve also mounted on the bottom wall of the toilet tank. Opening of the flapper valve causes water in the toilet tank to flow into the toilet bowl to flush the bowl. As the water level in the toilet tank decreases the inlet valve is opened and inflowing supply line water line passes through the inlet valve and is routed by the post into the toilet tank. After the water has drained from the toilet tank, the flapper valve returns to its closed position and the inflowing supply line water exiting from the post into the toilet tank refills the toilet tank. At the same time, an overflow tube, also disposed in the toilet tank, is in fluid communication with the toilet bowl for the purpose of filling the toilet bowl after a flush. A portion of the supply line water flowing through the inlet valve is directed into the overflow tube for the purpose of refilling the toilet bowl.
A continuing goal of designers of fill valve assemblies and, specifically, toilet fill valve assemblies, is to prevent or mitigate water loss or waste both during a flush/refill cycle after a Flush actuation and during a holding period between flash actuations. One potential source of water loss during a holding period is caused by a leakage of water from the toilet tank, for example, leakage of water from the toilet tank to the toilet bowl through a leaky flapper valve. Leakage of water from the toilet tank causes the water level in the toilet tank to gradually decrease. The float of the toilet fill valve assembly will move downwardly with the decreasing water level in the toilet tank. When the water level and the float position falls to a float trigger position, the inlet valve will open to refill the toilet tank and the toilet bowl (i.e., the inlet valve and the float will cause a water refill of the toilet tank as if a normal flush/refill cycle was occurring). If the leakage of water is not corrected and the holding period between flush actuations is long, the inlet valve may go through multiple water refill cycles of the toilet tank causing continued water loss over a long period before the leak is discovered and corrective action is taken by the owner to fix the leak. Additionally, since the inlet valve continues to periodically fill the toilet tank with supply line water, the owner of the toilet may not be aware of the leak as the toilet will appear to be functioning properly when used (that is, there will be sufficient water in the toilet tank to complete a flush when a flush actuation occurs), thus, the leakage problem may continued unabated for a prolonged period of time.
Another potential source of water loss results from overfilling the toilet bowl during a water refill cycle after a flush. Typically, a fill tube extends from the toilet fill valve assembly into an upper open end of the overflow tube. During a flush/refill cycle, a portion of the hallowing supply water passing through the inlet valve is routed through the fill tube and directed into overflow tube where the water flows into the toilet bowl to refill the toilet bowl. As the toilet tank is refilling and the inlet valve is open, if the volume of water routed through the fill tube is too great, the bowl will be overfilled during the flush/refill cycle. The excess water directed into the toilet bowl goes down the bowl drain. It would be desirable to have the volume of water flowing into the overflow tube during the flush/refill cycle of the toilet tank to be approximately equal to the volume of water desired for a complete bowl refill, without overfilling of the bowl, that is, without an appreciable amount of water flowing down the bowl drain during the flush/refill cycle.